Manufacture of alkaline cyanides



Patented 'Nov.' 20, 192s.

UNITED STATES PATENT OFFICE.

SYLVAIN COULIER, OF BRUSSELS, BELGIUM.

MANUFACTURE OF ALKALINE CYANIDES.

No Drawing. Application filed February 18, 1926, Serial No. 89,234, and in Belgium February 24, 1925.

This invention relates to an improved process for the manufacture of al iali-metal cyanides, in whichfree or combined nitrogen is caused to act at a high temperature upon a mixture of carbon and oneor more compounds of an'alkali metal the cyanide of which is to be produced.

Such a process is generally characterized by the use of an alkali carbonate mixed Lwith carbonaceous substances. The resultant mixture may be heated to a high temperature, and the re-acting-nitrogen may be derived from an air blast to which, moreover, ammonia may be added if desired.

1 The invention aims at .utilizing nitrogenous organic matter in a better way, and at producing alkali cyanides, starting from the said matter, in addition to other valuable products such as glycerine, fatty aeids,"acetone, methyl alcohol,-amines, ammonia, etc., which hitherto have'been obtained by the destructive distillation of the said matter.

The term nitrogenous organic. matter, is intended to cover any natural and residuary animal and vegetable matter adapted to be employed either as nitrogenous food for animals, or as nitrogenous fertilizers, or for the preparation of ferro-cyanides by the old method consisting in melting a mixture of these materials with alkalies in iron retorts. Such materials are, for example: animal fat and Waste, seaweed, pulp, bark and stones or kernals of alimentary plants and fruits; molasses and liquors derived from sugar 3.5 Works and distilleries; the residues from the treatment of hides, leather, bones, wool,feathers and hair; water and'sludge from sewerages; and worn materials, such as old leather, boots and shoes, exhaustedtanning'materials. 4 All these substantially-nitrogenous organic materials are mixed with alkalies or alkali carbonates unless they. already contain them; and the mixtures of these materials with alkali'es or alkali carbonates or only the constituents of the materials soluble in the latterare employed for the manufacture of alkali cyanides. I

- The present invention relates to a process of manufacturing alkali-metal cyanides which comprises the steps of distilling nitrogenous organic materials and then subjecting the distillation residue to the cyaniding When the action, at a temperature of between 800 and 1( )00 C. of the elemental nitrogen or the nitrogen compounds liberated in the course of distillation.

The cyaniding process may be carried out with the aid of known means and in any known 3,1" oaratus used for the purpose. The

alkaline carbonaceous residue is preferably crushed and sifted and the nitrogen gases may be used at ordinary or higher pressure.

7 When the process is applied to the utilizat1on of organic nitrogenous matter containing sulphur, for example, in the form of alkaline sulphates, the invention contemplates theuse of suitable desulphurizing agents such, for example, as alkaline earth oxides or'carbonates, metals such as iron and manganese-0r their oxides, and,,in general, all metals or compounds of metals capable of fixing sulphur in the state of sulphide. A desulphumzing agent, which may be employed is calcium carbonate, a residual product from the manufacture of sugar which is derived from the carbonization or saturation of the limed juice by carbon dioxide. y

process of the invention is to be applied to nltrogenous organic matter such as, for example, vinasses derived from molassee and containing free sulphuric acidcausing an acid reaction, the said acid may be neutralized by the addition of one or more of the above-mentioned substances before proced-v ing with destructive"distillation for obtaining the material to be cyanided, These additions are always proportional to the per centage of acids or of sulphates in the organic nitrogenous material utilized.

The alkaline carbonaceous residue to be cyanided'is preferably derived from very low temperature distillation of nitrogenous organic matter with alkali, and it generally retains a notable proportion ofthe nitrogen of the material treated. According to the 05 invention this residue is subjected to the action of heat in an autoclave before the free or combined nitrogen of the-"gases of'distilla= tion is caused to act on it. To this end, the residue is introduced into the autoclave,

,which is heated to a temperature of from 800 to 1000 (1, and thereafter the nitrogen is likewise introduced. The effect of this temperature, which is much higher than that of distillation, is to produce a more complete liberation of gas, so that the pressure in the autoclave rises and can reach several atmos-' pheres.

The alkali residue, already partially cyanided by this treatment, can then be subjected to the action of the gases of distillation, or simply that of the nitrogenous gases separated therefrom, as explained above. The cooled material is thereafter crushed and delivered to the cyaniding apparatus proper which may if necessary be the same as those used for distillation. All the operations: distillation, autoclave heating and heating with admission of distillation gases, cantake place in one and the same apparatus or in different apparatus.

Example 1.Old leather, leather scrap and tannery refuse'are suitably mixed with sodium carbonate and subjected to dry distilla tion in retorts gradually heated to 35 0 450-' G. preferably under reduced pressure. Disto 500 C. in whichit is distilled in the known manner under ordinary or moderate pressure. Distillation yields combustible gases, a condensation liquid containing" ammoniacal and amino compounds, oils and tar, and an alkali carbon residue retaining nitrogen. This alkali carbon residue is raised to a higher tem perature (800 to 1000 C.) in. a closed vessel or under pressure of nitrogen obtained from the non condensableand nitrogen-bearing gas stage of distillation. However, and preferably, these gases are burnt first and carbonic anhydride is separated therefrom in the known way. The aqueous portion of the condensation liquid obtained in distillation 1s decanted phuric acid. It is then first distilled in view of recovering fatty acids and methyl alcohol, and thereafter evaporated and concen-,

tillation begins atabout 100 6., and yields jt i th l j hi h i passed over th di combustible gases, an ammoniacal liquld, an tillation residue already partially cyanided oil and sometimes also tar. The distillation and heated to 800 C. to 1000 C.

residue is an alkaline carbonaceous residue Ew'ample 4.-L 'm e is addedto de-sugared and thereafter acidified by sulcontaining iron and copper from the molasses in suflicient proportion to decompose leather and perhapsr chromium oxlde 1f h thesalts of fatty acids and the amino and leather was tanned with chromium. These ammonia compounds. The thick mixture is metals and'thls oxide are very useful as subjected to destructive distillationinacloscd c ly in y n ng the alkali residue y vessel at moderate pressure and at a temperameans of nitrogen obtained from non-cont d ll i i t 300400 (1 A n g g s evolved durlng id n, monia, amines, acetic acid, methyl alcohol,

after combustion f d gases and separation light oils and tars are recovered in the cusof carbonic acid. The alkaline residue, heated t way Th a ueous ortion of the liq- Y to 800 to 1000 C in the presence of elG- uidozf condensation is distilled with milk of mental nitrogen, yields a cyan1ded\ lime which retains fatty acids while methyl forming the alkali-into cyanide.

sary for acting as a catalyzer.

mainly containing sodium cyanide an alcohol, ammonia and" trimethylamine are bOIli freed. Ammonia and the amines are ab- Ewample 2.Slaughterhouse offals are sorbed by sulphuric acid, ammonia loein trated solution of caustic-soda or caustic poth w Th th li o i distilled with ash heated. to a maxi um e p r lime and trimethylainine is utilized for cya- 9 resultmg P l mlxtm'e Q niding the alkaline carbonaceous matter (resimtrogenous and non'mtrogenous orgamc due of distillation) heated to 800 C. to materials and alkali) is thereafter gradually 1000 (1 nd if necessary previously d distilledundel reamed Pressure, first to tially cyanided in a closed vessel. or under for extracting g y ai nitrogen pressure, as in the preceding er- I up to 300-400 C. The vapoursevolved are 1 the recovery q g Example 5.Vinasse derived from molasf ammonlacal 19 1 1 and 0115- The ses and previously concentrated and with the l d- 'z condensatlon dBCaIItFd and addition of-a' desulphurizing agent capable treated in the usualw y for g g f g of forming a catalyzer in the residue, is submonla Whlch 15 then led Over the l'esldlle 0t jected to gradual distillation in a vacuum,

distillation, heated to 8001000 C- fOI with agitation and steaminjection, first at a Ewample 3.VinaSSe fI' m g -b -the recovery of glycerine, then at a temperalasses is concentrated under the addition of t r d ll i d t 550 (1 f {b carbon, sawdust, damag d pu p y Car-i covery of light tars, acetic acid, etc., and bonaoeous materi l, an a Sllfi'lclent P 19 amino compounds,'ammonia and combustible tion of pulverized i'ron or iron oxide, for fixgases t i i l t l itr g j Th ing the amount of sulphur when alkali metal whole of the'nitrogenous compounds or @10 sulphates are reduced by carbon, and if necesmental nitrogen only are then caused to act,

is supplied to a'retort heated to between 300 tion residue heated to a temperature suitable temperature between 200 C. and 300 C for 105 g d in an autoclave boiler in separated by=crystallizat ion f ammonia Sui for the preparation of alkali metal cyanide.

In each case, it is advisable to cause the gas least riclr in nitrogen to act upon fresh residue and to cause the gases richest in nitrogen to act upon partially cyanided residue.

In a similar manner, and with respect to Vinasscs and other nitrogenous organic matter, it may be desirable to collect most of the mythyl group (CH first and to use for cyaniding purposes, with preliminary dissociation, only the gases evolved at destruction heat, the latter varying with the nature and composition of the organic nitrogenous mat- Lter treated, but being generally between 200 and 300 C. Destructivedistillation may be also carried out-at a temperature not exceeding the latter or remaining in thevicinity thereof. In each case the residual material derived from distillation may be subjected to a partial and preliminary cyaniding process by residual nitrogen retained in the alkaline carbonaceous material, and carried out under pressure in a closed vessel. As previously stated the nitrogenous organic matter submitted to destructivedistillation may receive an addition of carbonaceous material if it is too rich in alkalies, or an addition of alkaline compounds if it'is too rich incarbon. These possible additions, like that of a catalyzer such as comminuted iron, iron oxide, halogen salts, etc; are preferably made before the nitrogenous organic'mattei' is subjected to distillation. These additions however may be made at any other stage of the process, in particular immediately before the residue of destructive distillationis preliminarily or finally cyanided. v

The organic matter concerned'maybe subjected to destructive distillation according to any known method and in any kndwn appa ratus. .The said distillation may' jliejadvane tageously carried out by agitating the mater al while it is distilled in order to obtain a divided saline residue which may be used straightaway for cyaniding, i. e. without requiring to be crushed.

When the cyaniding operation of the residual material is completed, the said material may be crushed and exhausted with water r for separating alkali metal cyanide from Insoluble substances which with .an excess of carbon contain sometimes the desulphurizing agent as a sulphide) added before distillation, and the catalyzer. The latter residual material may be subjected to a further treatment for separating the catalyzer and the carbon which may beused for de-colouring purposes or if necessary or desirable may be added together with the catalyzer to the organic nitrogenous matter before it is distilled for. the purpose of obtaining the correct proportioh of-carbon, catalyzer and alkali metal compounds used in the process for cyaniding the residue from distillation.

The cyanidd material may also be utilized to produce ammonia in the known way,

under recovery of alkali metal formates.

What I claim as my invention and desire to secure by Letters Patent is:

1. In a process of making alkali metal cyanides, the steps of distilling nitrogenous organic matter separating the relatively nonvolatile, non-nitrogenous substances from the rest of the distillate; and causing the elemental nitrogen liberated in the course of distillation to act, at a temperature between 800-1000 (3., upon the residue of distillation.

to effect cyanidation; the distillation step being carried out at a temperatureconsiderably below thatof the cyaniding step.

2. In a process of making alkali metal cyanides, the steps of distilling nitrogenous organic matter; separating the relatively non- I mental nitrogen and the amines liberated in the course of distillation to act, at atemperature between 800-1000 (1., upon the residue of distillation to effect cyanidation; the distillation step being carried out at a temperature considerably below that of the cyaniding at r- 1. In a process of making alkali metal cyanides, the steps of distillingnitrogenous organic matter; separating tars and water from the gaseous products of such distillation; and then causing the tar-free and waterfree nitrogenous gaseous products to act, at a temperature between 8001000 CL, upon the residue of distillation to effect cyanidation; the distillation step being carried out at a temperature considerably below that of the cyaniding step.

In a process of making alkali metal cyanides, the steps of distilling nitrogenous organic matter separating the relatively nonvolatile, non-nitrogenous substances from the.

rest of the distillate; introducing into a closed vessel the residue of distillation; heating said residue to a temperature between 800-1000 C. to fix the residual nitrogen of the. residue; i

and introducing the gaseous nitrogenous products of distillation into said vessel to act on the nitrified residue; the distillation step being carried out at a temperature considerably below that of the cyaniding step.

6. In a process of making alkali metal I cyanides, the steps of distilling nitrogenous organic matter; separating the relatively nonvolatile, non-nitrogenous substances from the rest of the distillate; heating the residue of distillation to a-temperature between 800- 55 l000 (1; then causing the gaseous nitrogenous products of distillation to act on the heated residue; cooling and crushing the para temperature considerably below that of thecyaniding step.

In testimony whereof I aflix m signature.

SYLVAIN C ULIER. 

